Chemistry and Physics. 87 



15. Entropy; or Thermodynamics from an Engineer's Stand- 

 point, and the Reversibility of Thermodynamics ; by James 

 Swinburne. Westminster. Pp. x + 137. (Archibald Constable 

 and Co.) — This book is the outcome of discussion carried on by 

 the author and others during the latter part of 1903 in the columns 

 of the London Engineering. This discussion has been of great 

 value in calling renewed attention to the importance and difficul- 

 ties of the thermodynamics of irreversible changes. Mr. Swin- 

 burne's contribution cannot, however, be said to be thoroughly 

 satisfactory, unless considered alone for its suggestiveness, and 

 for its rather amusing polemical rigor. In order to put more 

 emphasis on irreversible changes, which are the only real changes 

 occurring in nature, and in order to gain a more physical notion 

 of entropy, he proposes a new order of development of the prin- 

 ciples of the science. That these praiseworthy objects have been 

 successfully attained seems doubtful, though the suggestiveness 

 arising from the change in viewpoint cannot fail to be of value to 

 the thoughful reader. The accepted or orthodox (as Mr. Swin- 

 burne for controversial purposes prefers to call it) presentation of 

 the science starts with those laws of the transformation of energy 

 which are known as the two laws of thermodynamics ; then comes 

 the consideration of the reversible process and cycle from which, 

 by application of the second law, we get the idea of entropy and 

 its conservation; then passing to irreversible or actual processes, 

 we arrive at the notion of the waste in such processes and the 

 growth of entropy. The presentation proposed in this book 

 starts, as does the ordinary treatment, with the same two laws of 

 energy transformation, though Mr. Swinburne unnecessarily mars 

 the presentation by inserting a wholly gratuitous third law, l. e. 

 that a frictionless mechanism is unrealisable ; then follows the 

 consideration of the irreversible or actual process, the waste 

 incurred in such processes, the definition of entropy as the meas- 

 ure of the waste, and the doctrine of the growth of entropy; 

 then taking up the ideal reversible cycle, the working definition 

 or mathematical expression for the entropy (or rather for its 

 minimum value) is obtained. Now, aside from the pugnacious 

 manner in which it is presented, and leaving out the unessential 

 and unfortunate "third " law, there can be no valid objection to 

 looking at thermodynamics in this way if one so wishes ; in fact, 

 the reviewer feels under a great personal obligation to Mr. Swin- 

 burne for proposing this very suggestive alternative viewpoint. 

 When, however, he comes, in the third and fourth chapters, to 

 consider in detail certain irreversible changes, one cannot criticise 

 the author so favorably. There is a lamentable confusion in the 

 matter of the "heat of a bod} 7 ," and, in particular, the restriction 

 of the temperature, in the expression for entropy to the tempera- 

 ture of the envelope, cannot be admitted. A criticism of less 

 moment is that Mr. Swinburne's contention that the state of 

 development of a science is a function of the names it possesses 

 for its units, and that therefore thermodynamics will continue in 



